setwd("D:/R")
a1<-read.table("D:/R/ADdata1.txt",header=T,na.strings = c("NA"))
a2<-read.csv("D:/R/ADdata2.csv", header=T, na.strings=c("NA"))
a4<-read.table("D:/R/ADdata4.txt",header=T,na.strings = c("NA"))
mergedata<-merge(a1,a2,by.x= 0,by.y=1)
#install.packages("readxl")
library(readxl)
a3<-read_excel("D:/R/ADdata3.xlsx")
mergedata2<-merge(a3,a4,by.x=1,by.y=0)
result<-merge(mergedata,mergedata2,by.x=1,by.y=1)
